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            <h1>python基础 &gt; 运算符、表达式与内置对象</h1>
            <h2 class="subheading"></h2>
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              Posted by zhuang on
              2020-09-13
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        <h3 id="一、内置对象"><a href="#一、内置对象" class="headerlink" title="一、内置对象"></a>一、内置对象</h3><div class="table-container">
<table>
<thead>
<tr>
<th>对象类型</th>
<th>类型名称</th>
<th>示例</th>
<th>说明</th>
</tr>
</thead>
<tbody>
<tr>
<td>数字</td>
<td>int、float、complex</td>
<td>123,3.14,1.3e5,3</td>
<td></td>
</tr>
<tr>
<td>字符串</td>
<td>str</td>
<td>‘swfu’、”I’m s student”、‘’‘Python’‘’、r‘sbc’、R‘bcd’</td>
<td></td>
</tr>
<tr>
<td>字节串</td>
<td>bytes</td>
<td>b‘hello world’</td>
<td></td>
</tr>
<tr>
<td>列表</td>
<td>list</td>
<td>[1,2,3]、[‘a’,’b’,[‘c’,2]]</td>
<td></td>
</tr>
<tr>
<td>字典</td>
<td>dict</td>
<td>{1:’foot’,2:’taste’,3:’import’}</td>
<td></td>
</tr>
<tr>
<td>元组</td>
<td>tuple</td>
<td>(2,-5,6)、(3,)</td>
<td></td>
</tr>
<tr>
<td>集合</td>
<td>set、frozenset</td>
<td>{‘a’,’b’,’c’}</td>
<td></td>
</tr>
<tr>
<td>布尔型</td>
<td>bool</td>
<td>True、Flase</td>
<td></td>
</tr>
<tr>
<td>空类型</td>
<td>NoneType</td>
<td>None</td>
<td></td>
</tr>
<tr>
<td>异常</td>
<td>Exception、ValueError、TypeError</td>
<td></td>
<td></td>
</tr>
<tr>
<td>文件</td>
<td></td>
<td>f = open(‘data.dat’,’rd’)</td>
<td></td>
</tr>
<tr>
<td>其他迭代对象</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr>
<td>编程单元</td>
<td></td>
<td></td>
</tr>
</tbody>
</table>
</div>
<h4 id="1-常量与变量"><a href="#1-常量与变量" class="headerlink" title="1. 常量与变量"></a>1. 常量与变量</h4><p>在python中，</p>
<ul>
<li>不需要事先声明变量名及其类型</li>
<li>直接赋值即可创建任意类型的对象变量</li>
<li>变量的值可以变换，变量的类型可以发生改变</li>
</ul>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line">x = <span class="number">3</span>;</span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">type</span>(x));   <span class="comment">#内置函数type()用来查看变量类型 &lt;class &#x27;int&#x27;&gt;</span></span><br><span class="line"> </span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">type</span>(x) == <span class="built_in">int</span>); <span class="comment">#True</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">isinstance</span>(x,<span class="built_in">int</span>));  <span class="comment">#内置函数isinstance()用来测试变量是否为指定类型  True</span></span><br><span class="line"></span><br><span class="line">x = <span class="string">&quot;Hello World&quot;</span>;  <span class="comment">#字符串变量</span></span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">type</span>(x));    <span class="comment"># 之前的整型变量x不复存在  &lt;class &#x27;str&#x27;&gt;</span></span><br></pre></td></tr></table></figure>
<p>变量并不直接存储值，而是存储了值的内存地址或者引用。</p>
<p>变量出现在赋值运算符或符合赋值运算符(+=、* 、=等 )的左边表示创建变量或修改变量的值，否则表示引用该变量的值。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">x = <span class="number">3</span>;           <span class="comment">#创建整型变量</span></span><br><span class="line"><span class="built_in">print</span>(x ** <span class="number">2</span>);   <span class="comment">#访问变量的值  9</span></span><br><span class="line">x += <span class="number">6</span>;          <span class="comment">#修改变量的值</span></span><br><span class="line">x = [<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>];     <span class="comment">#创建列表对象  </span></span><br><span class="line">x[<span class="number">1</span>] = <span class="number">5</span>;        <span class="comment">#修改列表元素值</span></span><br><span class="line"><span class="built_in">print</span>(x);        <span class="comment">#输出显示整个列表 [1, 5, 3]</span></span><br><span class="line"><span class="built_in">print</span>(x[<span class="number">2</span>]);     <span class="comment">#输出显示列表指定元素 3</span></span><br></pre></td></tr></table></figure>
<p>Python中定义变量名问题：</p>
<ol>
<li>必须以字母或下划线开头</li>
<li>不能有空格或标点符号</li>
<li>不能用关键字</li>
<li>不建议使用系统内置的模块名，类型名或函数名以及导入的模块名及其成员名</li>
<li>变量名对英文字符的大小写敏感</li>
</ol>
<h4 id="2-数字"><a href="#2-数字" class="headerlink" title="2. 数字"></a>2. 数字</h4><h5 id="2-1-内置的整数、实数与复数"><a href="#2-1-内置的整数、实数与复数" class="headerlink" title="2.1 内置的整数、实数与复数"></a>2.1 内置的整数、实数与复数</h5><p>在对实数运算中，应尽量避免在实数之间直接进行相等性测试，而是应该二者之差的绝对值是否足够小作为两个实数是否相等的依据。</p>
<p>在算术运算表达式求值进行隐式的类型转换。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="built_in">print</span>(<span class="number">0.3</span> + <span class="number">0.2</span>);  <span class="comment">#实数相加   0.5</span></span><br><span class="line"><span class="built_in">print</span>(<span class="number">0.4</span> - <span class="number">0.1</span>);  <span class="comment">#实数相减   0.30000000000000004</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(<span class="number">0.4</span> - <span class="number">0.1</span> == <span class="number">0.3</span>);   <span class="comment">#应尽量避免直接比较两个实数是否相等   False</span></span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">abs</span>(<span class="number">0.4</span> - <span class="number">0.1</span> - <span class="number">0.3</span>) &lt; <span class="number">1e-6</span>); <span class="comment">#1e-6 表示10 的-6次方   True</span></span><br></pre></td></tr></table></figure>
<p>python内置支持复数类型运算。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">x = <span class="number">3</span> + <span class="number">4j</span>;     <span class="comment">#使用j和J表示复数的虚部</span></span><br><span class="line">y = <span class="number">5</span> + <span class="number">6j</span>;</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(x + y);         <span class="comment">#支持复数之间的加减乘除以及幂乘等运算 (8+10j)</span></span><br><span class="line"><span class="built_in">print</span>(x * y);         <span class="comment"># (-9+38j)</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(<span class="built_in">abs</span>(x));         <span class="comment">#内置函数abs()可用来计算复数的模</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(x.imag);         <span class="comment">#虚部      4.0</span></span><br><span class="line"><span class="built_in">print</span>(x.real);         <span class="comment">#实部      3.0</span></span><br><span class="line"><span class="built_in">print</span>(x.conjugate());  <span class="comment">#共轭复数  (3-4j)</span></span><br></pre></td></tr></table></figure>
<p>在数字中间位置使用单个下划线作为分隔符来提高数字的可读性。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="built_in">print</span>(<span class="number">1_000_000</span>);     <span class="comment">#1000000</span></span><br><span class="line"><span class="built_in">print</span>(<span class="number">1_2_3_4</span>);       <span class="comment">#1234</span></span><br></pre></td></tr></table></figure>
<h5 id="2-2-分数"><a href="#2-2-分数" class="headerlink" title="2.2 分数"></a>2.2 分数</h5><p>标准库<code>fractions</code>中的<code>Fractions</code>对象支持分数运算。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">from</span> fractions <span class="keyword">import</span> Fraction;</span><br><span class="line">x = Fraction(<span class="number">3</span>,<span class="number">5</span>);          <span class="comment">#创建分数对象</span></span><br><span class="line">y = Fraction(<span class="number">3</span>,<span class="number">7</span>);</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(x);</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(x.numerator);        <span class="comment">#分数中的分子</span></span><br><span class="line"><span class="built_in">print</span>(x.denominator);      <span class="comment">#分数中的分母</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(x ** <span class="number">2</span>);             <span class="comment">#分数的幂运算</span></span><br><span class="line"><span class="comment">#分数的之间的四则运算，自动进行通分</span></span><br><span class="line"><span class="built_in">print</span>(x + <span class="number">2</span>);</span><br><span class="line"><span class="built_in">print</span>(x - <span class="number">2</span>);</span><br><span class="line"><span class="built_in">print</span>(x * <span class="number">2</span>);</span><br><span class="line"><span class="built_in">print</span>(x / <span class="number">2</span>);</span><br><span class="line"><span class="comment">#分数与数字之间的运算  6/5</span></span><br><span class="line"><span class="built_in">print</span>(x * <span class="number">2</span>);</span><br><span class="line"><span class="comment">#把实数转换为分数  7/2</span></span><br><span class="line"><span class="built_in">print</span>(Fraction(<span class="number">3.5</span>));</span><br></pre></td></tr></table></figure>
<h5 id="2-3-高精度实数"><a href="#2-3-高精度实数" class="headerlink" title="2.3 高精度实数"></a>2.3 高精度实数</h5><p>标准库<code>fractions</code>中的<code>Decimal</code>类实现高精度的运算</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">from</span> fractions <span class="keyword">import</span> Decimal</span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(<span class="number">1</span>/<span class="number">9</span>);    <span class="comment">#0.1111111111111111</span></span><br><span class="line"></span><br><span class="line"><span class="built_in">print</span>(Decimal(<span class="number">1</span>/<span class="number">9</span>));  <span class="comment">#0.111111111111111104943205418749130330979824066162109375</span></span><br></pre></td></tr></table></figure>
<h4 id="3-字符串与字节串"><a href="#3-字符串与字节串" class="headerlink" title="3. 字符串与字节串"></a>3. 字符串与字节串</h4><ul>
<li>没有字符常量和变量，只有字符串类型的产量和变量。</li>
<li>使用单引号，双引号、三引号作为定界符，并且可以相互嵌套</li>
<li><code>Python 3.X</code> 全面支持中文，中文和英文字母作为一个字符对待，甚至可以使用中文作为变量名</li>
<li><code>Python 3.X</code>支持字节串类型<ul>
<li>对str类型调用<code>encode()</code>方法得到bytes字节串</li>
<li>对bytes类型调用<code>decode()</code>方法得到str字符串</li>
</ul>
</li>
</ul>
<h4 id="4-列表、元组、字典、集合"><a href="#4-列表、元组、字典、集合" class="headerlink" title="4. 列表、元组、字典、集合"></a>4. 列表、元组、字典、集合</h4><h3 id="二、Python运算符与表达式"><a href="#二、Python运算符与表达式" class="headerlink" title="二、Python运算符与表达式"></a>二、Python运算符与表达式</h3><h4 id="1-运算符优先级"><a href="#1-运算符优先级" class="headerlink" title="1. 运算符优先级"></a>1. 运算符优先级</h4><p>算术运算符（先乘除，后加减） &gt; 位运算符    &gt;   成员测试运算符   &gt;  关系运算符     &gt;   逻辑运算符   </p>
<p>圆括号是明确和改变表达式运算顺序的利器。</p>
<h4 id="2-算术运算符"><a href="#2-算术运算符" class="headerlink" title="2. 算术运算符"></a>2. 算术运算符</h4><h5 id="2-1-运算"><a href="#2-1-运算" class="headerlink" title="2.1 + 运算"></a>2.1 + 运算</h5><p>出来用于算术加法外，还可以用于列表、元组、字符串的连接。不支持不同类型对象之间相加或连接。</p>
<figure class="highlight python"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line">x = [<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>] + [<span class="number">4</span>,<span class="number">5</span>,<span class="number">6</span>];</span><br><span class="line"><span class="built_in">print</span>(x);   <span class="comment">#连接两个列表</span></span><br><span class="line"></span><br><span class="line">x = (<span class="number">1</span>,<span class="number">2</span>,<span class="number">3</span>) + (<span class="number">4</span>,);</span><br><span class="line"><span class="built_in">print</span>(x);   <span class="comment">#连接两个元组</span></span><br><span class="line"></span><br><span class="line">x = <span class="string">&#x27;abcd&#x27;</span> + <span class="string">&#x27;1234&#x27;</span>;</span><br><span class="line"><span class="built_in">print</span>(x);   <span class="comment">#连接两个字符串</span></span><br><span class="line"></span><br><span class="line">x = <span class="string">&#x27;A&#x27;</span> + <span class="number">1</span>;</span><br><span class="line"><span class="built_in">print</span>(x);   <span class="comment">#不支持字符和数字相加，抛出异常</span></span><br><span class="line"><span class="comment"># TypeError: can only concatenate str (not &quot;int&quot;) to str  </span></span><br><span class="line"></span><br><span class="line">x = <span class="literal">True</span> + <span class="number">3</span>;  <span class="comment">#把True当作1处理</span></span><br><span class="line"><span class="built_in">print</span>(x);      <span class="comment">#4</span></span><br><span class="line"></span><br><span class="line">x = <span class="literal">False</span> + <span class="number">3</span>; <span class="comment">#把False当作0处理</span></span><br><span class="line"><span class="built_in">print</span>(x);      <span class="comment">#3</span></span><br></pre></td></tr></table></figure>
<h5 id="2-2-运算"><a href="#2-2-运算" class="headerlink" title="2.2 -运算"></a>2.2 -运算</h5><h5 id="2-3-运算"><a href="#2-3-运算" class="headerlink" title="2.3 *运算"></a>2.3 *运算</h5><h5 id="2-4-和-运算"><a href="#2-4-和-运算" class="headerlink" title="2.4 /和//运算"></a>2.4 /和//运算</h5><h5 id="2-5-运算符"><a href="#2-5-运算符" class="headerlink" title="2.5 %运算符"></a>2.5 %运算符</h5>

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          <ol class="toc-nav"><li class="toc-nav-item toc-nav-level-3"><a class="toc-nav-link" href="#%E4%B8%80%E3%80%81%E5%86%85%E7%BD%AE%E5%AF%B9%E8%B1%A1"><span class="toc-nav-number">1.</span> <span class="toc-nav-text">一、内置对象</span></a><ol class="toc-nav-child"><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#1-%E5%B8%B8%E9%87%8F%E4%B8%8E%E5%8F%98%E9%87%8F"><span class="toc-nav-number">1.1.</span> <span class="toc-nav-text">1. 常量与变量</span></a></li><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#2-%E6%95%B0%E5%AD%97"><span class="toc-nav-number">1.2.</span> <span class="toc-nav-text">2. 数字</span></a><ol class="toc-nav-child"><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-1-%E5%86%85%E7%BD%AE%E7%9A%84%E6%95%B4%E6%95%B0%E3%80%81%E5%AE%9E%E6%95%B0%E4%B8%8E%E5%A4%8D%E6%95%B0"><span class="toc-nav-number">1.2.1.</span> <span class="toc-nav-text">2.1 内置的整数、实数与复数</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-2-%E5%88%86%E6%95%B0"><span class="toc-nav-number">1.2.2.</span> <span class="toc-nav-text">2.2 分数</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-3-%E9%AB%98%E7%B2%BE%E5%BA%A6%E5%AE%9E%E6%95%B0"><span class="toc-nav-number">1.2.3.</span> <span class="toc-nav-text">2.3 高精度实数</span></a></li></ol></li><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#3-%E5%AD%97%E7%AC%A6%E4%B8%B2%E4%B8%8E%E5%AD%97%E8%8A%82%E4%B8%B2"><span class="toc-nav-number">1.3.</span> <span class="toc-nav-text">3. 字符串与字节串</span></a></li><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#4-%E5%88%97%E8%A1%A8%E3%80%81%E5%85%83%E7%BB%84%E3%80%81%E5%AD%97%E5%85%B8%E3%80%81%E9%9B%86%E5%90%88"><span class="toc-nav-number">1.4.</span> <span class="toc-nav-text">4. 列表、元组、字典、集合</span></a></li></ol></li><li class="toc-nav-item toc-nav-level-3"><a class="toc-nav-link" href="#%E4%BA%8C%E3%80%81Python%E8%BF%90%E7%AE%97%E7%AC%A6%E4%B8%8E%E8%A1%A8%E8%BE%BE%E5%BC%8F"><span class="toc-nav-number">2.</span> <span class="toc-nav-text">二、Python运算符与表达式</span></a><ol class="toc-nav-child"><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#1-%E8%BF%90%E7%AE%97%E7%AC%A6%E4%BC%98%E5%85%88%E7%BA%A7"><span class="toc-nav-number">2.1.</span> <span class="toc-nav-text">1. 运算符优先级</span></a></li><li class="toc-nav-item toc-nav-level-4"><a class="toc-nav-link" href="#2-%E7%AE%97%E6%9C%AF%E8%BF%90%E7%AE%97%E7%AC%A6"><span class="toc-nav-number">2.2.</span> <span class="toc-nav-text">2. 算术运算符</span></a><ol class="toc-nav-child"><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-1-%E8%BF%90%E7%AE%97"><span class="toc-nav-number">2.2.1.</span> <span class="toc-nav-text">2.1 + 运算</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-2-%E8%BF%90%E7%AE%97"><span class="toc-nav-number">2.2.2.</span> <span class="toc-nav-text">2.2 -运算</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-3-%E8%BF%90%E7%AE%97"><span class="toc-nav-number">2.2.3.</span> <span class="toc-nav-text">2.3 *运算</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-4-%E5%92%8C-%E8%BF%90%E7%AE%97"><span class="toc-nav-number">2.2.4.</span> <span class="toc-nav-text">2.4 &#x2F;和&#x2F;&#x2F;运算</span></a></li><li class="toc-nav-item toc-nav-level-5"><a class="toc-nav-link" href="#2-5-%E8%BF%90%E7%AE%97%E7%AC%A6"><span class="toc-nav-number">2.2.5.</span> <span class="toc-nav-text">2.5 %运算符</span></a></li></ol></li></ol></li></ol>
        
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		<!-- Search -->
		
		<div class="popup search-popup local-search-popup">
  <span class="popup-btn-close">
    ESC
  </span>
  <div class="container">
    <div class="row">
      <!-- <div class="col-md-9 col-md-offset-1"> -->
      <div class="col-lg-9 col-lg-offset-1 col-md-10 col-md-offset-1 local-search-content">

        <div class="local-search-header clearfix">

          <div class="local-search-input-wrapper">
            <span class="search-icon">
              <i class="fa fa-search fa-lg" style="margin: 25px 10px 25px 20px;"></i>
            </span>
            <input autocomplete="off" placeholder="搜索..." type="text" id="local-search-input">
          </div>
        </div>
        <div id="local-search-result"></div>
      </div>
    </div>
  </div>
</div>


  
    <script src="/js/ziploader.js"></script>
  
  <script>
    // Popup Window;
    var isfetched = false;
    var isXml = true;
    // Search DB path;
    var search_path = "search.json";
    if (search_path.length === 0) {
      search_path = "search.xml";
    } else if (/json$/i.test(search_path)) {
      isXml = false;
    }
    // monitor main search box;
    var onPopupClose = function (e) {
      $('.popup').fadeOut(300);
      $('#local-search-input').val('');
      $('.search-result-list').remove();
      $('#no-result').remove();
      $('body').css('overflow', '');
    }

    function proceedsearch() {
      $('.popup').fadeIn(300);
      var $localSearchInput = $('#local-search-input');
      $localSearchInput.attr("autocapitalize", "none");
      $localSearchInput.attr("autocorrect", "off");
      $localSearchInput.focus();
    }
    // get search zip version
    $.get('/searchVersion.json?t=' + (+new Date()), function (res) {
      if (localStorage.getItem('searchVersion') !== res) {
        localStorage.setItem('searchVersion', res);
        initSearchJson();
      }
    });

    function initSearchJson() {
      initLoad(['/search.flv'], {
        loadOptions: {
          success: function (obj) {
            localStorage.setItem('searchJson', obj['search.json'])
          },
          error: function (e) {
            return console.log(e)
          }
        },
        returnOptions: {
          'json': TYPE_TEXT
        },
        mimeOptions: {
          'json': 'application/json'
        }
      })
    }
    // search function;
    var searchFunc = function (search_id, content_id) {
      'use strict';
      isfetched = true;
      var datas = JSON.parse(localStorage.getItem('searchJson'));
      // console.log(search_id)
      var input = document.getElementById(search_id);
      var resultContent = document.getElementById(content_id);
      var inputEventFunction = function () {
        var searchText = input.value.trim().toLowerCase();
        var keywords = searchText.split(/[\s\-]+/);
        if (keywords.length > 1) {
          keywords.push(searchText);
        }
        var resultItems = [];
        if (searchText.length > 0) {
          // perform local searching
          datas.forEach(function (data) {
            var isMatch = false;
            var hitCount = 0;
            var searchTextCount = 0;
            var title = data.title
              ? data.title.trim()
              : '';
            var titleInLowerCase = title.toLowerCase();
            var content = data.content
              ? data.content.trim().replace(/<[^>]+>/g, "")
              : '';
            var contentInLowerCase = content.toLowerCase();
            var articleUrl = decodeURIComponent(data.url);

            var date = data.date;
            var dateTime = date.replace(/T/, " ").replace(/.000Z/, "");
            var imgUrl = data.header_img;
            


            var indexOfTitle = [];
            var indexOfContent = [];
            // only match articles with not empty titles
            keywords.forEach(function (keyword) {
              function getIndexByWord(word, text, caseSensitive) {
                var wordLen = word.length;
                if (wordLen === 0) {
                  return [];
                }
                var startPosition = 0,
                  position = [],
                  index = [];
                if (!caseSensitive) {
                  text = text.toLowerCase();
                  word = word.toLowerCase();
                }
                while ((position = text.indexOf(word, startPosition)) > -1) {
                  index.push({position: position, word: word});
                  startPosition = position + wordLen;
                }
                return index;
              }
              indexOfTitle = indexOfTitle.concat(getIndexByWord(keyword, titleInLowerCase, false));
              indexOfContent = indexOfContent.concat(getIndexByWord(keyword, contentInLowerCase, false));
            });
            if (indexOfTitle.length > 0 || indexOfContent.length > 0) {
              isMatch = true;
              hitCount = indexOfTitle.length + indexOfContent.length;
            }
            // show search results
            if (isMatch) {
              // sort index by position of keyword
              [indexOfTitle, indexOfContent].forEach(function (index) {
                index.sort(function (itemLeft, itemRight) {
                  if (itemRight.position !== itemLeft.position) {
                    return itemRight.position - itemLeft.position;
                  } else {
                    return itemLeft.word.length - itemRight.word.length;
                  }
                });
              });
              // merge hits into slices
              function mergeIntoSlice(text, start, end, index) {
                var item = index[index.length - 1];
                var position = item.position;
                var word = item.word;
                var hits = [];
                var searchTextCountInSlice = 0;
                while (position + word.length <= end && index.length != 0) {
                  if (word === searchText) {
                    searchTextCountInSlice++;
                  }
                  hits.push({position: position, length: word.length});
                  var wordEnd = position + word.length;
                  // move to next position of hit
                  index.pop();
                  while (index.length != 0) {
                    item = index[index.length - 1];
                    position = item.position;
                    word = item.word;
                    if (wordEnd > position) {
                      index.pop();
                    } else {
                      break;
                    }
                  }
                }
                searchTextCount += searchTextCountInSlice;
                return {hits: hits, start: start, end: end, searchTextCount: searchTextCountInSlice};
              }
              var slicesOfTitle = [];
              if (indexOfTitle.length != 0) {
                slicesOfTitle.push(mergeIntoSlice(title, 0, title.length, indexOfTitle));
              }
              var slicesOfContent = [];
              while (indexOfContent.length != 0) {
                var item = indexOfContent[indexOfContent.length - 1];
                var position = item.position;
                var word = item.word;
                // cut out 100 characters
                var start = position - 20;
                var end = position + 80;
                if (start < 0) {
                  start = 0;
                }
                if (end < position + word.length) {
                  end = position + word.length;
                }
                if (end > content.length) {
                  end = content.length;
                }
                slicesOfContent.push(mergeIntoSlice(content, start, end, indexOfContent));
              }
              // sort slices in content by search text's count and hits' count
              slicesOfContent.sort(function (sliceLeft, sliceRight) {
                if (sliceLeft.searchTextCount !== sliceRight.searchTextCount) {
                  return sliceRight.searchTextCount - sliceLeft.searchTextCount;
                } else if (sliceLeft.hits.length !== sliceRight.hits.length) {
                  return sliceRight.hits.length - sliceLeft.hits.length;
                } else {
                  return sliceLeft.start - sliceRight.start;
                }
              });
              // select top N slices in content
              var upperBound = parseInt('1');
              if (upperBound >= 0) {
                slicesOfContent = slicesOfContent.slice(0, upperBound);
              }
              // highlight title and content
              function highlightKeyword(text, slice) {
                var result = '';
                var prevEnd = slice.start;
                slice.hits.forEach(function (hit) {
                  result += text.substring(prevEnd, hit.position);
                  var end = hit.position + hit.length;
                  result += '<b class="search-keyword">' + text.substring(hit.position, end) + '</b>';
                  prevEnd = end;
                });
                result += text.substring(prevEnd, slice.end);
                return result;
              }
              var resultItem = '';

              // if (slicesOfTitle.length != 0) {   resultItem += "<li><a target='_blank' href='" + articleUrl + "' class='search-result-title'>" + highlightKeyword(title, slicesOfTitle[0]) + "</a>"; } else {   resultItem += "<li><a target='_blank' href='" +
              // articleUrl + "' class='search-result-title'>" + title + "</a>"; } slicesOfContent.forEach(function (slice) {   resultItem += "<a target='_blank' href='" + articleUrl + "'><p class=\"search-result\">" + highlightKeyword(content, slice) +
              // "...</p></a>"; }); resultItem += "</li>";

              if (slicesOfTitle.length != 0) {
                resultItem += "<a target='_blank' href='" + articleUrl + "' class='search-result'><div class='search-result-left'><div class='search-result-title'>" + highlightKeyword(title, slicesOfTitle[0]) + "</div><time class='search-result-date'>" + dateTime + "</time>";
              } else {
                resultItem += "<a target='_blank' href='" + articleUrl + "' class='search-result'><div class='search-result-left'><div class='search-result-title'>" + title + "</div><time class='search-result-date'>" + dateTime + "</time>";
              }
              slicesOfContent.forEach(function (slice) {
                resultItem += "<p class=\"search-result-content\">" + highlightKeyword(content, slice) + "...</p>";
              });
              resultItem += "</div><div class='search-result-right'><img class='media-image' src='" + imgUrl + "' width='64px' height='48px'></img></div></a>";

              resultItems.push({item: resultItem, searchTextCount: searchTextCount, hitCount: hitCount, id: resultItems.length});
            }
          })
        };

        if (keywords.length === 1 && keywords[0] === "") {
          resultContent.innerHTML = '<div id="no-result"></div>'
        } else if (resultItems.length === 0) {
          resultContent.innerHTML = '<div id="no-result"></div>'
        } else {
          resultItems.sort(function (resultLeft, resultRight) {
            if (resultLeft.searchTextCount !== resultRight.searchTextCount) {
              return resultRight.searchTextCount - resultLeft.searchTextCount;
            } else if (resultLeft.hitCount !== resultRight.hitCount) {
              return resultRight.hitCount - resultLeft.hitCount;
            } else {
              return resultRight.id - resultLeft.id;
            }
          });
          var searchResultList = '<div class=\"search-result-list\">';
          resultItems.forEach(function (result) {
            searchResultList += result.item;
          })
          searchResultList += "</div>";
          resultContent.innerHTML = searchResultList;
        }
      }
      if ('auto' === 'auto') {
        input.addEventListener('input', inputEventFunction);
      } else {
        $('.search-icon').click(inputEventFunction);
        input.addEventListener('keypress', function (event) {
          if (event.keyCode === 13) {
            inputEventFunction();
          }
        });
      }
      // remove loading animation
      $('body').css('overflow', '');
      proceedsearch();
    }
    // handle and trigger popup window;
    $('.popup-trigger').click(function (e) {
      e.stopPropagation();
      if (isfetched === false) {
        searchFunc('local-search-input', 'local-search-result');
      } else {
        proceedsearch();
      };
    });
    $('.popup-btn-close').click(onPopupClose);
    $('.popup').click(function (e) {
      e.stopPropagation();
    });
    $(document).on('keyup', function (event) {
      var shouldDismissSearchPopup = event.which === 27 && $('.search-popup').is(':visible');
      if (shouldDismissSearchPopup) {
        onPopupClose();
      }
    });

    document.addEventListener('mouseup', (e) => {
      var _con = document.querySelector(".local-search-content");
      if (_con) {
        if (!_con.contains(e.target)) {
          onPopupClose();
        }
      }
    });
  </script>


		
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    MathJax.Hub.Queue(function() {
        var all = MathJax.Hub.getAllJax();
        for (var i = 0; i < all.length; ++i)
            all[i].SourceElement().parentNode.className += ' has-jax';
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